In gas reactors or enclosed environments, in which critical gas concentrations may be present, gas measurements are necessary in order to detect gases being released or too high concentrations of toxic or explosive gases. The environment-related variables in the gas reactors or in the enclosed environments are frequently critical, i.e., very cold, very hot and/or highly reactive. The necessary gas-warning devices cannot therefore be used directly in these critical environments. The effort needed for safe gas removal for gas measurement/gas warning is very high in case of uncritical temperatures as well.
Extracting the gas by means of SIL (safety integrity level)-approved pumps from the measuring environment and passing the gas through a likewise SIL-approved filter stage, in which the gas is released from condensates (e.g., water) and possibly cooled, is known. The cleaned and cooled gas may then be fed to a gas-warning device. However, the high installation and maintenance efforts needed are drawbacks. Further, the result of the gas measurement is obtained with a time delay, which is due to the filtering, the distance traveled by the gas in the filter section and the cooling off of the gas.
Guiding visible light by means of optical fibers by collimation lenses through a reaction chamber is known from CN 102 062 726 A. This light is fed to a measuring device with an additional optical fiber. The optical fibers are attached to a bracket, which is arranged within the reaction chamber. Such an arrangement is not suitable for large volumes of gas, because the optical measured section through the reactor would be so long that the entire light fed in would be absorbed. Further, the installation and maintenance effort needed in this form of measurement is also very high since the bracket for the optical fibers is arranged within the reaction chamber. For installation, the bracket has to be inserted with effort and has to be removed with high effort for maintenance, which also comprises a cleaning of deposits of reactive gases.